Belgian research hints at 17th century roots for HIV

BRUSSELS, Belgium (Reuters) -- A predecessor of HIV, the virus that has killed millions, may have been around in humans as early as the 17th century, according to international researchers.

Using new computerized dating methods based on virus genetic data, Belgian scientists claim to have tracked links back over 300 years between HIV and a similar virus found in chimpanzees.

"Using this method, the group found that HIV-1 group M and its closest related simian virus SIVcpz, isolated from chimpanzees, shared a common ancestor about 300 years ago, around 1675," the Catholic University in Leuven, Belgium said in a statement.

One of the scientists, Leuven's Professor Anne-Mieke Vandamme, told Reuters the study confirmed that HIV-1 group M, the most common AIDS virus today, had begun to spread in humans before the 1920s and 1930s.

"Somewhere between the 17th century and early 1900s the virus made the jump from chimpanzees to humans.

"The 1920s-1930s is the moment that the (HIV) sub-types emerged, which means that the virus was in humans and started to evolve and diverge and accumulate," Vandamme said.

The origin of HIV, the virus that causes AIDS, is one of the 21st century's biggest medical mysteries. It is widely accepted that the virus jumped the "species barrier" from chimpanzees to humans, but no one is certain how, or when, this happened.

The study is a fresh blow to a controversial theory that HIV was spread to humans via polio vaccination programs in Africa in the 1950s which were alleged to have used batches of vaccine contaminated with the precursor virus found in chimps.

Vandamme subscribes to the "natural" theory that the virus was passed from chimp to man through hunting and then spread via war and migration in Africa early last century.

"Transmission took place through hunting and butchering chimpanzees for their meat. The virus then just stayed in villages, spreading gradually in Africa," Vandamme said.

"But, with mass migration, with people from the countryside going to the cities -- around the 1960s and 1970s -- then the virus started to spread, partly through increased promiscuity."

The Belgian scientists, helped by German, Irish, French and Senegalese researchers, developed a new computer method to analyze date time intervals for past epidemiological events.

This looks at differences in the genetic makeup of HIV-1 sub-types -- there are believed to be 12 of these -- and asks how long these differences took to evolve. The reliability of the results can be checked against historical viral samples. The study's preliminary findings were aired in mid-September at a special meeting of the British Royal Society. Full data is to be published early next month in the Federation of American Societies for Experimental Biology (FASEB) journal.

The World Health Organization reckons nearly 22 million people have died from HIV/AIDS in the last 20 years. Over five million people will have been infected this year.

Copyright 2000 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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